The present invention is directed to a compact disk (CD) player, and more specifically to a CD player that resumes supplying audio information without the hesitation normally attributed to disk access time.
As is well known to one of ordinary skill in the art, a typical audio compact disk (CD) is generally made of a polycarbonate with one or more metal layers. Information on a typical audio CD is encoded as a digital xe2x80x980 xe2x80x99 or a digital xe2x80x981 xe2x80x99 depending upon the presence or absence of pits in the surface of the CD. The audio information is read from the CD by a read head assembly, included within a CD player. A typical read head assembly includes an infrared laser diode, a reflecting mirror and a focusing lens. The laser diode emits a beam of light that is aimed at the reflecting mirror. The emitted light reflects off the mirror and through the focusing lens, which directs the light onto a specific point on the surface of the CD. The conventional read head assembly moves across the CD on a set of rails, similar to a head assembly of a floppy disk drive. The position of the read head assembly is controlled by a servo system that is controlled by a processor embedded within the CD player.
A certain amount of light, which depends upon where on the surface of the CD the light beam strikes, is reflected from the CD. A series of collectors, mirrors and lenses collect and provide the reflected light to a photodetector. The photodetector transforms the received reflected light into electrical energy with the level of the signal being dependent upon how much light was reflected from the CD. The level of the transformed signal determines whether the information read was a digital xe2x80x980 xe2x80x99 or a digital xe2x80x981xe2x80x99.
A spindle motor of the CD player rotates the CD such that the information can be read from the CD. The spindle motor employed in a standard CD player is typically different from that of a conventional hard drive or floppy drive in that the spindle motor in a CD player may not spin at a constant speed. That is, in some CD players, the speed of the spindle motor varies depending upon what part of the disk (inside or outside) is being read. In CD players that vary the spindle motor speed, when the read head assembly is positioned near the radial outside edge of the disk, the motor runs slower, as compared to when it is positioned radially inward where the motor runs faster. This reading technique, known as constant linear velocity (CLV), was implemented to ensure the same amount of data was read from a CD, each second, irrespective of what part of the CD was being accessed.
The CLV reading technique was necessary because, historically, CD players did not have the necessary intelligence or memory to allow them to deal with information arriving at different rates. In CD players of this type, the speed of the spindle motor is usually tied to the positioning of the read head assembly. Typically, the information coming from the CD is used to synchronize the speed of the motor and make sure the CD is running at the correct speed. An alternative technology utilized in some CD players, known as constant angular velocity (CAV), rotates the CD at a constant speed regardless of what area of the disk is being accessed.
A typical CD-ROM, utilized with a personal computer system, can transfer both data and audio information. When transferring audio information from a CD, the information is transferred directly to a sound card, via an audio cable. However, when the CD-ROM is transferring data, the data is transferred to a processor of the computer system. If the data is a music file (e.g., .wav file), the music file is then typically transferred to a sound card. A typical CD-ROM drive includes an interface (e.g., an intelligent drive electronics (IDE) interface, enhanced IDE interface, an advanced technology attachment packet interface (ATAPI), a small computer system interface (SCSI), a standard parallel interface, or a proprietary interface) that connects the CD-ROM drive to the computer system. The CD-ROM drive may further include a stereo headphone output, a volume control dial, start and stop buttons, and next track and previous track buttons.
Historically, CDs were read-only storage devices (e.g., audio CDs and compact disk-read-only memories (CD-ROMs)). However, today a number of writeable CDs, such as compact disk-rewriteable (CD-RW), compact disk-recordable (CD-R) and various types of digital versatile disks (DVDs) are commercially available. Most CD-RW, CD-R and DVD drives are considered backwards compatible with CD-ROMS and audio CDs. Most CD drives that are utilized to store data (e.g., applications), for use with a computer system, have on-board memory that is used to buffer data that is read from a CD. However, this on-board memory has generally not been used to buffer audio information as audio information has typically been provided directly to the audio system (e.g., a sound card) as it is read from the CD. On the other hand, automotive CD players that have electronic skip protection normally buffer audio information in conjunction with this feature.
During normal use of an audio system, a user typically may change from a CD player to a radio subsystem or alternatively to a tape subsystem. When this transition occurs, the spindle motor of the CD player is typically turned off or deactivated. As a result, when a user reselects the CD player, the audio system cannot output audio information until the CD spins up to the reading speed and the read head assembly is moved into position. During this time, the conventional audio system is not providing sound. This delay is typically in the range of 4 to 5 seconds, which is long enough that many users of the audio system may become confused as to whether an appropriate switch or command was received by the audio system. During this delay time, the user may push various buttons of the audio system or adjust the volume control up thinking it was turned down. In the latter case, when the audio information is provided, the audio information may be unpleasantly loud.
As such, a CD player that minimizes the hesitation normally attributed to disk access time is desirable. More particularly, a CD player that almost immediately provides audio information such that a user knows that their selection was received by the audio system is desirable.
The present invention is directed to a method and system that allows a disk drive to resume supplying audio information without the hesitation normally attributed to disk access time. Initially, an indication is received that the disk drive should be deactivated. Next, audio information is stored from a beginning position, where audio information was last provided, to a resume position. Then, the resume position at which the disk drive should begin retrieving audio information, when the disk drive is reactivated, is stored. Finally, when the disk drive is reactivated, the stored audio information is supplied without the hesitation normally attributed to the disk access time of the disk drive. In one embodiment, the resume position corresponds to a period that is at least equal in time to an access time of the disk drive.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.